There is work on self driving trains. In our university we worked on a project called autoBahn which made a proof of concept self driving train and I know of a

There is work on self driving trains. In our university we worked on a project called autoBahn which made a proof of concept self driving train and I know of a few other research projects that worked in the same direction. However, in my opinion there are several aspects why this is developing much slower than self driving cars: * There are incredibly many regulations for every single piece of hardware that can be used on a train. They have such strict regulations that computing hardware that is certified for use on trains is usually 2 generations behind current hardware. * There are not that many test tracks and you can't just roll your own track without fronting huge sums to build a test track. A self driving car can at least be driven on a private land if you don't have access to a test track and in the minimal case it does not have much more requirements than basically a paved parking area. * If you want to do the testing on a real track (we were lucky and had a partner company that enabled us to use a public track) you have to slot into the regular transit schedule. Which means a lot of planning to do a single test and then a very tight schedule to get the test system up and running. If you miss the allotted time you have to wait or scrap the test completely for that day. * An obvious issue is passenger safety. Even in a small train you can have several dozens of passengers which is a huge regulatory hurdle. * And the last and in my opinion very important thing is that you can get a testing vehicle for self driving cars up and running for a reasonable amount of money, sure they are more expensive than regular cars if you count all the sensors and hardware you need but it is nothing compared to a train car which is at least one order of magnitude more expensive. Also a huge issue is weather. In good weather conditions, self-driving <cars/trains/...> can handle themselves rather well but as soon as the weather gets bad or during the night it gets quite tricky. For example: We had situations where snow was completely covering the track for huge parts of the way. What should the algorithm that checks for obstacles on the track do if the whole track has vanished? The human driver has to rely on his gut feeling to decide if he can continue or not. We also had situations where quite a bit of vegetation was covering the tracks. The question is: Does this count as an obstacle that requires breaking or can you drive over it. As far as I know this was also an issue in the DARPA driving challenge where a car was driving over some grass which popped up after the car passed over it causing the sensors in the back to report an obstacle and which prevented it from backing out of the situation.